Traditional man-made optical systems are comprised of multiple lenses wherein one or more of the lenses are physically displaced to realize variable-focus. Nature, however, accomplishes this same function much more elegantly with an individual lens. For example, in the human eye, ciliary muscles are controlled by the body's nervous system, thereby relaxing and contracting the shape of a human eye lens to enable the eye to focus on different distances. Although advancements in miniaturization technologies have led to single microlens embodiments that are widely used in photonics, displays, and biomedical systems, these microlens technologies rely on either fixed focal length or externally-controlled variable-focus microlenses.
By way of example, Berge et. al., U.S. Pat. No. 6,369,953 discloses a variable-focus lens that utilizes a voltage potential to vary the focal length. More specifically, the lens includes a dielectric chamber having a drop of a transparent, insulating liquid deposited on an inner surface thereof. The dielectric chamber is filled with a transparent, conductor liquid. The insulating liquid and the dielectric liquid have different optical indexes and have substantially the same density. A first electrode is placed on the external surface of the wall of the dielectric chamber on which is situated the insulating drop. A second electrode is electrically coupled to the conductor liquid. When a voltage is established between the first and second electrodes, an electric field is created which causes the conductor liquid to move and deform the insulating liquid. This, in turn, results in a variation in the focus of the intersection of the insulating liquid and the conducting liquid, or in other words, the lens.
While functional for their intended purpose, these prior microlenses have certain inherent limitations. For example, prior variable-focus lenses generally have a small tuning range of focal lengths. Further, in order to increase the flexibility in the design and operation of the microlens in various applications, it is highly desirable for the mircolens to be responsive to various environmental parameters presented in such applications. However, since the prior microlenses utilize external controls, such self-regulation is not feasible. It must also be noted when the prior microlenses are used to observe a biological sample, the voltage used to manipulate the focal length of the microlens may have an adverse effect on the sample. Consequently, it is highly desirable to provide a variable-focus microlens that is self-regulating and that allows for the tuning of the microlens without any external control or power consumption.
Therefore, it is a primary object and feature of the present invention to provide a variable-focus optical microlens that is autonomously tuned by local environmental parameters.
It is a further object and feature of the present invention to provide a variable-focus optical microlens that automatically adjusts the focal length thereof without the need for external control systems.
It is a still further object and feature of the present invention to provide a variable-focus optical microlens that is compact and easily fabricated.
In accordance with the present invention, a variable-focus lens assembly is provided. The lens assembly includes a slip having first and second sides and an inner wall defining an aperture therethrough. A lens is disposed across the aperture. A hydrogel structure engages the slip. The hydrogel structure is movable between a first configuration wherein the lens has a first focal length and a second configuration wherein the lens has a second focal length in response to a predetermined stimulus.
The variable-focus lens assembly also includes a base and the hydrogel structure is generally ring-shaped and defines a cavity therethrough. The hydrogel structure is disposed between the base and the second side of the slip such that the cavity communicates with the aperture though the slip. Alternatively, the hydrogel structure may include a plurality of circumferentially spaced posts disposed between the base and the second side of the slip about the aperture though the slip.
The lens may be fabricated from a transparent film or from first and second layers having an interface. The interface has an outer periphery that is pinned to the inner wall of microfluidic device. It is contemplated for the first layer to be formed from an oil-based fluid and the second layer to be formed from a water-based fluid.
In accordance with a further aspect with the present invention, a variable-focus lens assembly is provided. The lens assembly includes a microfluidic device defining a chamber for receiving a fluid therein. A lens is disposed in the chamber and has a tunable focal length. A tuning structure is provided for tuning the focal length of the lens in response to a predetermined stimulus.
The lens assembly also includes a base and a slip spaced from the base. The slip has an aperture therethough. The tuning structure includes a hydrogel disposed between the slip and the base. The hydrogel has a configuration alterable between a first configuration wherein the lens has a first focal length and a second configuration wherein the lens has a second focal length in response to the predetermined stimulus. Alternatively, the tuning structure may include a plurality of circumferentially spaced posts disposed between the base and the second side of the slip about the aperture though the slip. Each post has a configuration alterable between a first configuration and a second configuration in response to the predetermined stimulus.
The lens may be fabricated from a transparent film or from first and second layers having an interface. The interface has an outer periphery that is pinned to an inner wall of the slip. It is contemplated for the first layer to be formed from an oil-based fluid and the second layer to be formed from a water-based fluid.
In accordance with a still further aspect of the present invention, a variable-focus lens assembly is provided. The lens assembly includes a microfluidic device defining a chamber for receiving a fluid therein. A slip is disposed in the chamber. The slip has first and second sides and an inner wall defining an aperture therethrough. A first fluid is disposed on the first side of the slip and a second fluid is disposed on the second side of the slip. A lens having a focal length is positioned at the boundary of the first and second fluids. A tuning structure tunes the focal length of the lens in response to a predetermined stimulus.
The variable-focus lens assembly includes a base spaced from the slip and the tuning structure includes a hydrogel ring disposed between the slip and the base. The ring has a configuration alterable between a first configuration wherein the lens has a first focal length and a second configuration wherein the lens has a second focal length in response to the predetermined stimulus. Alternatively, the tuning structure may include a plurality of circumferentially spaced posts disposed between the base and the second side of the slip about the aperture though the slip. Each post has a configuration alterable between a first configuration and a second configuration in response to the predetermined stimulus.
The lens may be fabricated from a transparent film or from first and second layers having an interface. The interface has an outer periphery that is pinned to the inner wall of the slip. It is contemplated for the first layer to be formed from an oil-based fluid and the second layer to be formed from a water-based fluid.